Liquid fuel feeding and burning apparatus



Dec. 9, 1947. R. w. DE LANCEY LIQUID FUEL FEEDING AND BURNING APPARATUSFiled Nov. 13, 1943 2 Sheets-Sheet 1 4 w I w INVENTOR IPALPH W OELA/VCEYATTORNEY Dec. 9, 1947. R. w. DE LANCEY 2,432,143

LIQUID FUEL FEEDING AND BURNING APPARATUS Filed Nov. 13, 1943 2Sheets-Sheet 2 INVENTOR w I RALPH W. DELANCEY MM ATTORNEY Patented Dec.9, 1947 LIQUID FUEL FEEDING AND BURNING APPARATUS Ralph W. De Lancey,Meriden, Conn., assignor to The Miller Company, Meriden, Conn.) acorporation of Connecticut Application November 13, 1943, Serial No.510,18 2

1 24 Claims.

The present invention relates to liquid fuel feeding and burningapparatus of the gravity fed vaporizing type.

Gravity fed vaporizing type burners are usually (on. 15s- -91) tions inwhich the tipping is insufflcient'to permit the liquid to back up intothe passages.

According to the preferred construction'the fuel feeding apparatus andthe vaporizer are consupplied with fuel by a combined constant level 5structed as a'single 'unitwherein thefuel chamvalve and metering valveconnected to the burner br' and the vaporizer pot are in a singlecasting, bowl and both the valve and bowl are permathe pot is associatedwithsuitable air controlling nently installed at a precise level so thatduring and distributing devices to facilitate combustion, ordinary highthe operations there is a pool of. and the fuel supply chamber has asuitablefloat liquid in the burner. Its highest levelis detervalve andmetering valve which may be assomined by the constant level valveadjustment ciated with suitable manual and automatic conand its actualdepth depends upon the rate of trols shown and claimed in applicationsSerial supply through the metering valve and the com- Nos. 510,183 and510,184 filed concurrently herebustion rate. In such installations thecombusa with. I I tion rate is very materially changed by anything Thepresent invention also contemplates that affecting the height of theliquid surface in the the fuel delivered to the vaporizer will be burnedburner so that such burners are entirely ununder forced draft. Theburner is connected suited for use in other than installations whichwith a combustion drum by a vertical fire tube, can be' leveled and keptlevel. and according to the preferred construction the The presentinvention contemplates apparatus forced draft is carried down through atube confor feeding and burning liquid fuel in gravity centric with thefire tube and the air is distributed fed vaporizing burners which may beembodied to the vaporizing pot. The preferred mode of in portableheaters whose operation is not afdistribution of the air totthevaporizing pot is fected by wide departures of the apparatus from tocause part of the air to go up through a centhe level. tral tubularriser in the pot and direct the re- This makes it possible to not onlydisregard maining air down into the pot from above and leveling of theapparatus, but to deliberately set into a lower combustion zone througha suitably it up where it is very far from the level and to placedperforated sleeve sothat most of the comuse it on moving vehicles andboats where bustion of fuel takes place closely adjacent the changes inlevel and speed of movement are unvaporizer. avoidable. It is thuspossible to employ the com- A furtherobject of the present invention isparatively inexpensive pot type burner in locato provide the vaporizingburner with a suitable tions where such use has heretofore beenimvaporization accelerator which conducts heat possible, and the burningof liquid fuel restricted from the combustion zone down to the vaporizerto gun type, rotary type and wick type burners. so as to keep thevaporizer hot and assist in According to the present invention theburner volatilizing the liquid fuel.

is normally substantially below the discharge The preferred form ofapparatus shown and opening of the metering valve and connected toclaimed in the present application is designed it by a passage downwhich the fuel drains to the more particularly for use in the warm airheatvaporizer. The flow rate of the metering valve ing furnace shown andclaimed in my applicais dependent almost entirely on the hydrostatic-tion Serial No. 510,181 filed concurrently herehead maintained at itsoutlet by'a float valve with. and'the extent of its opening, and as aresult Other and further objects will hereinafter apthe amount of fuelsupplied to the vaporizer has pear as the description proceeds. norelation to the difference in level between the The accompanyingdrawings show, for purfuel in the float valve chamber and the vaporizerposes of illustrating the present invention, an level, at least untilthe tipping of the organizaembodiment in which the invention may taketion is so great as to bring the bottom of the form, together withmodification of certain parts, vaporizer up substantially to the levelof the it being understood that the drawings are illusliquid in thefloat chamber. trative of the invention rather than limiting the Thecombustion capacity of the burner is same. higher than the fuel feedingrate so that when In these drawings: v the burner is in ordinaryoperation the vaporizer Figure 1 is a front elevational view of theliquid remains substantially dry and no liquid can acfuel feeding andburning apparatus showing a cumulate below the metering valve in allposiportion of the Warm air heating furnace;

Figure 2 is a vertical sectional view taken on the line 22 of Figure 1;

Figure 3 is a horizontal sectional view taken on the broken line 3-3 ofFigures 1 and 2;

Figure 4 is an elevational view taken from the left of Figure 1 withparts in section on the line 4--4 of Figures 1, 3 and 5, and looking inthe direction of the arrows;

Figure 5 is a vertical sectional view on the line 5-5 of Figures 2, 3and 4, and looking in the direction of the arrows; and

Figure 6 is a fragmentary sectional view through a pot burner adaptedfor non-portable use.

The bottom housing unit A of the warm air furnace has a semi-cylindricalbottom housing member 20, to which is welded a tubular burner housing2|. This burner housing tube extends below the bottom housing member 20as indicated at 2|a (Figure 5) and above it as indicated at 2|b. Theunit A also has legs 22 for support.

The combustion drum C has an outer cylindrical body 24, and end wallsone of which is shown at 25. These end walls have aligned openings 21,which receive air tubes 28. The bottom part of the drum body 24 isprovided with an opening 29 in which is welded a downward extending firetube 38. It will be noted from the drawings that this fire tube is nearone end of the combustion drum and that the lower air tubes 28 arespaced apart substantially the same distance as the diameter of the firetube 30. The upper edge of the tube 2| engages the lower surface of thedrum 24 in the side away from the end wall 25 so as to provide anopening 31 for supplying air to the burner.

In order to provide a blast of air through the furnace the open rear endof the housing accommodates a blower whose fan is indicated at M. Theblower unit not only blows air through the tubes 28 to be heated, butalso causes a blast of air to pass down through the space between thefire tube 38, and the tubular burner housing 2| to supply the burner B.A deflector 51 is employed to guide a portion of the blast of air fromthe fan into this down draft passage.

The fuel supply tank shown fragmentarily at I delivers fuel to thestrainer J through pipes 62 and 63. These two pipes are connected to thediagonally opposite corners of the tank, so that fuel can be drainedfrom the tank when the furnace is substantially out of level.

The strainer J may be of conventional construction and may be secured inany convenient way to the bottom. of the housing. It carries a shut offvalve 84, biased to closed position and operable to an open position bya lever 65. The discharge pipe from the strainer is indicated at 66 andit leads into the fuel control valve forming a, part of the burnercontrol valve unit B.

The body casting of the burner valv control unit B is designated by thereference character 18. It has a float chamber H which is closed off bya cover 12, fastened in place by screws 12. The cover has a rearwardlyextending tubular coupling element 13 for coupling to the fuel pipe 66.A float 16 controls an inlet valve so that the fuel depth may bemaintained in the float chamber. The casting 18 is provided with anoutlet valve seat insert 18 at the bottom of the float chamber, whichcooperates with a metering valve stem I9 urged upwardly by a spring 89and downwardly by mechanisms to be described. This valve forms themetering valve for the burner,

The constant level valve and metering valve are under manual control forthe purpose of starting and stopping the burner and are under automaticcontrol for the purpose of emergency shut-down of the burner as well asfor the con tinuous control of the metering valve for normal continuousoperation. These controls will now be described. They are more fullyshown and described in the applications above referred to.

The starting lever for opening the fuel pipe into the fuel chamber II isshown at 8|. It is pivoted at 82 to the U-shaped stamping 82 carried bythe cover member and has a general horizontally extending arm 83,'whichoverlies the top of the cover member 12. When it is in the positionshown in Figures 1, 4 and 5, the inner end of this arm 89 is latched inthis position by a lever 84 pivoted at 85 to the stamping 82' and havinga rear extension 86.

When the starting lever 8| is latched in this normal operating position,the arm 83 presses down On a pin 81 which extends through the floatchamber cover 12 and normally rests on the top of a leaf spring 88. Thisleaf spring is carried by the under side of the cover 12 and is normallyurged upwardly. It is free of the float mechanism when in that position,but when the starting lever 8| is in the shut off position, as indicatedin dot-and-dash lines in Figure 1, the pressure on the leaf spring 88 isremoved and this spring is able to act on the float mechanism, so as tomove it into the position to move the valve 15 to closed position and atthe same time it will lock the float mechanism against vibration duringshipment or transportation of the burner.

The starting lever 5) adapted to act stamping 82' at 9| coiled spring92.

8| has a cam 89 (see Figure on a lever 98 pivoted to the and urgeddownwardly by a The lever 98 carries a leaf spring 93 whose position canbe adjusted by high fire adjustment screw 94. The free end of the spring93 extends above shoulder 95 On the valve stem 19 and is out of contactwith this shoulder when the parts are in starting position. The spring93, however, limits the height to which the metering valve stem may bemoved by the coiled spring 88.

In order to prevent overheating of the burner, there is provided abimetallic safety device which includes a resilient bimetallicthermostat 96 suitably mounted in the space between the tubes 2| and 39and this bimetallic member is adjustable through mechanism shown indetail in my applications concurrently filed herewith Serial Nos.510,181 and 510,183. The bimetallic member 96 carries an extension 98which enters a notched element 99 extending rearwardly from the latchlever 84 and acts as a spring for the latch. Should overheating occur,the thermostat 96 will expand and operate the latch lever to release thestarting lever 8|, causing the mechanism to go to the shut-off position,so that no further fuel will be supplied to the chamber II and themetering valve will be closed so that no fuel will flow to the burner.

When the starting lever 8| is shifted to open the valves and the furnaceis cold, the metering valve will open to an extent determined by the airtemperature control unit L in a manner described more fully in theapplications above referred to. The fuel will then be allowed to flowthrough the metering valve at a predetermined rate which is the properrate (more than pilot and less than maximum fire) for starting theburner.

The fuel will pass down a sloping passage I05, see Figure 5, and enterthe vaporizer I06, forming the other end of the body 10 of the burnerunit B.

The vaporizer I06 has a central air tube I01 extending upwardly from thebottom of the pot and a row of downwardly and inwardly extending airholes or drillings I08. The vaporizer carries a perforated sleeve I09,preferably having larger holes at the top than at the bottom and thissleeve is clamped in position by a ring I I and bolts II I. The ring II0 is just the proper size to fit into the fire tube 30 and this tube isprovided with a bead I I2 to provide a stop for the ring. The ring isprovided with perforations II3, shown more clearly in Figure 3, andcarries upwardly extending rods II4 which support a flame spreadingplate H5. The ring IIO also carries a downwardly and outwardly flaringskirt I I6 which terminates just above the top of the vaporizer I06. Theskirt compels the air to pass underneath it to where air is preheated.This sk-irt also acts to prevent flame from passing out through thesleeve I09 and up the tube 2I. The bottom of the vaporizer I 06 iscovered by the cup shaped stamping II! to provide an air space H8 andfacilitate maintaining the vaporizer at a high temperature.

The unit B for the burner and fuel valve assembly is supported from thetube 2| by screws II9I I9 which passthrough holes in the tubes 2| and 30and are threaded into ring H0 and by screws I20 which pass through holesin a bracket I2I welded to tube 2I and are threaded into the casting 10.

The bottom of the down draft tube 2| is closed off by a hemisphericalstamping I22, which fits into the ring I23 carried by the bottom of thetube 2I and it is removably held in place by screws I24 threaded intoring I23. The casting 10 has a constriction as indicated at I25 whichimpedes the flow of heat lengthwise of the body member "I0. The riser orair tube I01 receives a ring I26 which carries a number of bent heatresisting wire elements of good thermal conducting material.

' These elements extend up into the combustion space and carry beat downinto the bottom of the vaporizer.

The liquid fuel burner illustrated in Figures 1 to 5 has been found tooperate entirely satisfactorily when supplied with aviation gasoline,ordinar gasoline, Diesel fuel oil, or light domestic fuel oil and attemperatures from arctic temperatures to tropical temperatures, so thatthe same equipment is suitable for practically any use within itscapacity. A two inch vaporizer is suitable for a firing rate up to about40,000 B. t. u.s per hour.

A lighting tube I30 is carried on the front side of the furnace andextends through down draft tube 2I and the fire tube 30. A cover I3I ispivoted on brackets I32 and urged to the open or to the closed positionby a leaf spring I33, as indicated in Figure 2.

A reciprocating rod or slider I49 (whose lower end is guided in a holeI50) is operated upon by an air temperature responsive thermostaticapparatus shown more fully in the applications above referred to, butfor present purposes it is believed suiflcient to say that when theapparatus is cold the bracket member I5I carried by slider I49 isbrought against nut I53 on valve stem 19 Where it limits the opening ofthe metering valve stem to an amount less than that allowed by the highfire stop 94. As the thermal apparaopen for maximum fire and then asheating continues proceeds to cut down the fire to a low flame. As thefurnace cools the firing rate is raised. The intensity of the fire,therefore, varies between the maximum and minimum, so that there is nolikelihood of overheating the parts, or delivering the air at too high atemperature, or of extinguishment of the flame.

It will thus be seen that when the structure is cold or at ordinary roomtemperatures the extent of openingof the metering valve will be controlled by the adjustment of the stop mechanism for the air temperatureresponsive thermostat, and that when the starting lever 0| is moved tothe starting position the fuel pipewill be opened to the float chamber,and fuel at a predetermined flow rate will pass down to the burner. Thisfuel will form a pool in the burner and must be immediately lighted. Iffor any reason the metering valve is allowed to remain open too longbefore the torch is supplied, the oil can flow from the vaporizer outthrough the tube I01 and escape through a drain hole I22 in the stampingI22. The lighting can be done by inserting a torch T (such as indicatedin Figure 1) through the lighting tube I 30. The fuel will be consumedin the burner and the natural draft caused by the combustion of the fuelwill cause the products of operation, the motor or engine as to operatethe fan and blow air through'the furnace and through the burner.

When the furnace is level, as shown in the drawings, the passage I05slopes downwardl at about 18 to the horizontal. The fuel cannotaccumulate in the passage so in the flow rate is immediately followed bya change in rate of combustion. The maximum combustion rate of theburner under either natural draft or forced draft is greater than thecapacity of the metering valve to deliver fuel, so that there is nosubstantial accumulation of fuel in the vaporizer. The vaporizer istherefore normally substantiall dry. A tilting of the furnace (in adirection to lower the float chamber) through an angle of 10 isindicated by dot-anddash lines in Figure 5. The passage. I05 stillslopes downwardly toward the vaporizer and, only a very small amount offuel can flow back into the passage. Tilting sidewise or in a directionto raise the float chamber also causes no accumulation of fuel in thepassage. It will thus be seen that the furnace may be far out of levelwithout impairing operation, and that sudden changes in the tilting ofthe furnace will make no substantial change. So long as the level of thefuel surface in the float valve is sufficiently above the vaporizer andthere is suitable hydraulic head on the metering valve the furnace cancontinue in operation. This makes it possible to ignore matters ofleveling of the furnace and to use it on moving vehicles and boats, or

When the burner has been sufby natural draft operation to perthat anychange a wardly from the same reference characters are applied. Thevaporizer I06 and perforated sleeve I09 are received in a housing Hadapted to be kept under positive pressure by a blower (not shown). Thevaporization accelerator I21 is made of a number of wires weldedtogether at the top and extending down to the tube I01. This acceleratorserves to conduct heat down to the bottom of the vaporizer,

Since it is obvious that the invention may be embodied in other formsand constructions within the scope of the claims, I wish it to beunderstood that the particular form shown is but one of these forms, andvarious modifications and changes being possible, I do not otherwiselimit myself in any way with respect thereto,

What is claimed is:

1. A gravity fed liquid fuel burner adapted to operate when tipped awayfrom a level position through substantial angles in any directioncomprising an annular vaporizing pot with a central air tube extendingupwardly from the bottom of steep outer side walls extending upthebottom of the pot, a fuel supply passage extending upwardly andlaterally from the pot, a fuel receiving and storing chamber rigid withthe pot, and a flow regulating valve between the chamber and passage.

2.. In a gravity fed liquid fuel burner for operation at substantialdepartures from normal level position and comprising a single castinghaving an annular vaporizing pot, a fuel supply chamber disposedlaterally of the pot and normallyat a substantially higher level thanthe top of the pot, a fuel passage interconnecting the pot and supplychamber and normally sloping upwardly from adjacent the bottom of thepot whereby only a limited amountof fuel may be stored in the fuelpassage for flowing into the pot on tilting the burner to lower the potrelative to the supply chamber and no fuel can flow from the pot intothe passage until the burner is tilted to lower the supply chamber sothat the passage becomes substantially horizontal. 1

3. In apparatus for gravity feeding and buming liquid fuel, a cast bodyhaving a float chamber at one end, a vaporizing pot at the other end andat normally a lower elevation than the bottom of the float chamber whenin use, a tubular portion providing a passage connecting the chamber andpot to drain liquid fuel from the chamber to the pot, and a housingabout the vaporizing pot and having an aperture through which the castbody extends so that the float chamber is exterior of the housing, thecast body having a restricted cross section adjacent the pot whereby thepot may be kept hot to facilitate vaporization of fuel and flow of heatto the float chamber is impeded.

4. In a liquid fuel burner, an annular vaporizer having a centrallydisposed, upwardly extending air tube which forms an annular trough forliquid fuel, means forming a fuel supply passage leading to the trough,an upwardly extending perforated sleeve extending upwardly from theperiphery of the vaporizer, the periphery of the vaporizer havingdownwardly and inwardly converging air holes, and means for subjectingthe outside of the sleeve and vaporizer to a pressure above atmosphericto form air jets directed inwardly of the sleeve and down into thevaporizer and a stream of air which passes up through the centrallydisposed tube, whereby vaporization takes place in the zone below thetop of the sleeve, and combustion ensues.

the pot and 5. In a liquid fuel burner, an annular vaporizer having acentrally disposed, upwardly extending air tube which forms an annulartrough for liquid fuel, means forming a fuel supply passage leading tothe trough, an upwardly extending perforated sleeve extending upwardlyfrom the periphery of the vaporizer, the periphery of the vaporizerhaving downwardly and inwardly converging air holes. means forsubjecting the outside of the sleeve and vaporizer to a pressure aboveatmospheric to form air jets directed inwardly of the sleeve and downinto the vaporizer and a stream of air which passes up through thecentrally disposed tube, whereby vaporization takes place in the zonebelow the top of the sleeve, and combustion ensues, and heating meansfor the trough and fuel therein comprising conducting elements extendingfrom the bottom of the trough upwardly to be heated by the fuel burnedfrom the vaporizer.

6. In a liquid fuel burner, an annular vaporizer, a perforated sleeveextending upwardly from the periphery of the vaporizer to form acombustion chamber, a ring at the top of the sleeve the ring having anopening slightly smaller than the sleeve for escape of flame and gasesand vertical peripheral openings outside the sleeve to direct air jetsinto the rising flame and gases, upwardly and inwardly extending rodscarried by the ring, and a flame spreading disc carried by the rodsabove the ring.

7. In a liquid fuel burner, an annular vaporizer having a centrallydisposed, upwardly extending air tube which forms an annular trough forliquid fuel, means forming a fuel supply passage leading to the trough,an upwardly extending perforated sleeve extending upwardly from theperiphery of .the vaporizer, the periphery of the vaporizer havingdownwardly and inwardly converging holes, a ring at the top of thesleeve, the ring having a central opening smaller than the sleeve andperipheral openings therethrough outside the sleeve, means subjectingthe ouside of the sleeve, the vaporizer and ring to pressure aboveatmospheric to form air jets directed down into the vaporizer andupwardly above the ring and a stream of air which passes up through thecentrally disposed tube, whereby vaporization takes place in the zonebelow the opening in the ring, combustion ensues, and the flame anduncon sumed gases pass upwardly within the air jets above the ring.

8. A burner as claimed in claim 7, having heat conducting elementsextending from the bottom of the trough upwardly into the combustionzone for acceleration of vaporization of fuel in the trough.

9. A burner as claimed in claim '7, having rods secured to the ring anda flame spreading disc carried by the rods.

10. A burner as claimed in claim '7, having heat conducting elementsextending from the bottom of the trough upwardly into the combustionzone for acceleration of vaporization of fuel in the trough, rodssecured to the ring, and a flame spreading disc carried by the rods.

11. A liquid fuel burner comprising a trough a burner housing extendingdown from the drum to enclose the fire tube, the sleeve and thevaporizer, the top of the burner housing having a lateral forced draftair admission opening,

12. A burner as claimed in claim 11, having a skirt-like memberextending downwardly from the periphery of the ring so that all the airmust pass below the skirt before it can pass through the sleeve or ring.

13. A burner as claimed in claim 11, having a flame spreader above thering.

14. A burner as claimed in claim 11, wherein the vaporizing pot hasdownwardly and inwardly converging holes for directing air toward thebottom of the pot.

15. In combination, a furnace body having a downwardly extending downdraft tube adapted to be supplied with a blast of air from an extraneoussource, a combustion drum having a downwardly extending fire tube insideof and concentric with the draft tube, a preassembled liquid fuel burnerunit having a vaporizing pot, a perforated sleeve extending upwardlyfrom the pot, and a ring at the top of the sleeve and secured to thepot, the ring being secured in the fire tube to support the unit, thering, sleeve and pot having openings for admitting air for combustion, aclosure member surrounding the pot and fitted about the lower end of thedown draft tube to maintain the air pressure on the outside of theburner unit, a fuel tank above the level of the pot, and a fuel supplyconduit from the tank to the pct.

16. The combination of claim 15, having a flame spreader carried by thering and extending up into the fire tube.

17. The combination of claim 15, having a skirt carried by the ring andspaced outside the perforatedsleeve to compel the down draft air to gobelow the skirt before it can pass through the openings.

18. The combination claimed in claim 15, wherein the draft tube and firetube have aligned openings, and having a laterally extending lighterreceiving tube secured to the fire tube and extending out through thedraft tube, and a normally closed door for the lighter receiving tube.

19. In combination, a furnace body having a downwardly extending downdraft tube adapted to be supplied with a blast of air from an extraneoussource, and a combustion drum having a downwardly extending fire tubeinside of and concentric with the draft tube, a pre-assembled liquidfuel supply and burner unit having a casting forming a vaporizing potand a fuel supply chamber and having a downwardly sloping fuel passageconnecting-the chamber and pot, a perforated sleeve extending upwardlyfrom the pot, a ring at the top of the sleeve and secured to the 'pot,the ring being secured in the fire tube to support the unit, the ring,sleeve and pot having openings for admitting air for combustion, a floatoperated constant level valve in the chamber, and a metering valve forcontrolling rate of fuel flow, and a closure member surrounding the potand fitted about the lower end of the down draft tube to maintain theair pressure on the outside of the burner unit, the portion of thecasting having the fuel supply chamber being outside of and laterally ofthe down draft tube.

20. A liquid fuel burner having a fuel vaporizing pot, a housing aroundand spaced from the pot substantially closed below the pot and extendingabove the pot, a source of forced draft for blowing air down thehousing, a perforated sleeve the pot and having combustion chamberclosing off the housing about the fire tube, so that chest.

21. A liquid fuel burner having a fuel vaporizing pot, a perforatedsleeve extending upwardly from the pot forming a primary combustionchamber, a fire tube above the combustion chamber at the top of the firetube, and a housing about the potand fire tube to form an air chest andhaving a lateral opening at a level substantially higher than the potfor receiving air for combustion.

22. An apparatus for ing fuel, comprising an annular vaporizing pot forburning liquid fuel in a combustion zone above side walls provided withdownair holes, and a central tubular nearly up to the level of the thehousing forms an air wardly converging element extending holes in theside air stream to the zone of combustion and provid-- ing an overflow,and a fuel supply source at a level above that of the top of the tubularelement whereby rise in fuel level in the pot is limited by the tubularmember, the airholes being above the overflow level.

23. In combination, an annular vaporizing pot for burning pot-containedliquid fuel in a combustion zone above the pot and having a centrallydisposed upwardly opening overflow tube extending from the bottom of theburner pot to provide a central air supply discharged upwardly at thecenter of the pot slightly above the liquid therein, means formaintaining a continuous supply of fuel, and a vaporization acceleratorincluding a ring about the tube, and heat resisting wires of goodthermal conductivity extending upwardly from the ring and bent onthemselves so that their lower ends extend close to the bottom of thepot.

24. The combination of claim 23, having a perforated sleeve extendingupwardly from the periphery of the pot at least as high as thevaporization accelerator to admit air into the combustion zone.

RALPH W. DE LANCEY.

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